066c258587
- Rebased patches: 165, 170, 198 - Refactored patches: 289 - Removed patches (included upstream): 280, 283, 284, 285, 287, 293, 297, 298, 299
280 lines
10 KiB
Diff
280 lines
10 KiB
Diff
diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
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index 7e47b2d..12a210d 100644
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--- a/Lib/test/test_gc.py
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+++ b/Lib/test/test_gc.py
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@@ -1,7 +1,8 @@
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import unittest
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from test.support import (verbose, run_unittest, start_threads,
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- requires_type_collecting)
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+ requires_type_collecting, import_module)
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import sys
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+import sysconfig
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import time
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import gc
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import weakref
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@@ -39,6 +40,8 @@ class GC_Detector(object):
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self.wr = weakref.ref(C1055820(666), it_happened)
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+BUILT_WITH_NDEBUG = ('-DNDEBUG' in sysconfig.get_config_vars()['PY_CFLAGS'])
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+
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### Tests
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###############################################################################
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@@ -537,6 +540,49 @@ class GCTests(unittest.TestCase):
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# would be damaged, with an empty __dict__.
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self.assertEqual(x, None)
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+ @unittest.skipIf(BUILT_WITH_NDEBUG,
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+ 'built with -NDEBUG')
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+ def test_refcount_errors(self):
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+ # Verify the "handling" of objects with broken refcounts
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+
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+ import_module("ctypes") #skip if not supported
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+
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+ import subprocess
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+ code = '''if 1:
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+ a = []
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+ b = [a]
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+
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+ # Simulate the refcount of "a" being too low (compared to the
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+ # references held on it by live data), but keeping it above zero
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+ # (to avoid deallocating it):
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+ import ctypes
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+ ctypes.pythonapi.Py_DecRef(ctypes.py_object(a))
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+
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+ # The garbage collector should now have a fatal error when it reaches
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+ # the broken object:
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+ import gc
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+ gc.collect()
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+ '''
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+ p = subprocess.Popen([sys.executable, "-c", code],
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+ stdout=subprocess.PIPE,
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+ stderr=subprocess.PIPE)
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+ stdout, stderr = p.communicate()
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+ p.stdout.close()
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+ p.stderr.close()
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+ # Verify that stderr has a useful error message:
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+ self.assertRegexpMatches(stderr,
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+ b'Modules/gcmodule.c:[0-9]+: visit_decref: Assertion "gc->gc.gc_refs != 0" failed.')
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+ self.assertRegexpMatches(stderr,
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+ b'refcount was too small')
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+ self.assertRegexpMatches(stderr,
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+ b'object : \[\]')
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+ self.assertRegexpMatches(stderr,
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+ b'type : list')
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+ self.assertRegexpMatches(stderr,
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+ b'refcount: 1')
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+ self.assertRegexpMatches(stderr,
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+ b'address : 0x[0-9a-f]+')
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+
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class GCTogglingTests(unittest.TestCase):
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def setUp(self):
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gc.enable()
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diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
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index 916e481..0233ce2 100644
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--- a/Modules/gcmodule.c
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+++ b/Modules/gcmodule.c
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@@ -21,6 +21,73 @@
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#include "Python.h"
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#include "frameobject.h" /* for PyFrame_ClearFreeList */
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+/*
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+ Define a pair of assertion macros.
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+
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+ These work like the regular C assert(), in that they will abort the
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+ process with a message on stderr if the given condition fails to hold,
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+ but compile away to nothing if NDEBUG is defined.
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+
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+ However, before aborting, Python will also try to call _PyObject_Dump() on
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+ the given object. This may be of use when investigating bugs in which a
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+ particular object is corrupt (e.g. buggy a tp_visit method in an extension
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+ module breaking the garbage collector), to help locate the broken objects.
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+
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+ The WITH_MSG variant allows you to supply an additional message that Python
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+ will attempt to print to stderr, after the object dump.
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+*/
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+#ifdef NDEBUG
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+/* No debugging: compile away the assertions: */
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+#define PyObject_ASSERT_WITH_MSG(obj, expr, msg) ((void)0)
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+#else
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+/* With debugging: generate checks: */
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+#define PyObject_ASSERT_WITH_MSG(obj, expr, msg) \
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+ ((expr) \
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+ ? (void)(0) \
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+ : _PyObject_AssertFailed((obj), \
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+ (msg), \
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+ (__STRING(expr)), \
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+ (__FILE__), \
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+ (__LINE__), \
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+ (__PRETTY_FUNCTION__)))
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+#endif
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+
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+#define PyObject_ASSERT(obj, expr) \
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+ PyObject_ASSERT_WITH_MSG(obj, expr, NULL)
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+
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+static void _PyObject_AssertFailed(PyObject *, const char *,
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+ const char *, const char *, int,
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+ const char *);
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+
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+static void
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+_PyObject_AssertFailed(PyObject *obj, const char *msg, const char *expr,
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+ const char *file, int line, const char *function)
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+{
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+ fprintf(stderr,
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+ "%s:%d: %s: Assertion \"%s\" failed.\n",
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+ file, line, function, expr);
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+ if (msg) {
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+ fprintf(stderr, "%s\n", msg);
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+ }
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+
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+ fflush(stderr);
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+
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+ if (obj) {
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+ /* This might succeed or fail, but we're about to abort, so at least
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+ try to provide any extra info we can: */
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+ _PyObject_Dump(obj);
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+ }
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+ else {
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+ fprintf(stderr, "NULL object\n");
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+ }
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+
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+ fflush(stdout);
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+ fflush(stderr);
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+
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+ /* Terminate the process: */
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+ abort();
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+}
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+
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/* Get an object's GC head */
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#define AS_GC(o) ((PyGC_Head *)(o)-1)
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@@ -328,7 +395,8 @@ update_refs(PyGC_Head *containers)
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{
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PyGC_Head *gc = containers->gc.gc_next;
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for (; gc != containers; gc = gc->gc.gc_next) {
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- assert(gc->gc.gc_refs == GC_REACHABLE);
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+ PyObject_ASSERT(FROM_GC(gc),
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+ gc->gc.gc_refs == GC_REACHABLE);
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gc->gc.gc_refs = Py_REFCNT(FROM_GC(gc));
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/* Python's cyclic gc should never see an incoming refcount
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* of 0: if something decref'ed to 0, it should have been
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@@ -348,7 +416,8 @@ update_refs(PyGC_Head *containers)
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* so serious that maybe this should be a release-build
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* check instead of an assert?
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*/
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- assert(gc->gc.gc_refs != 0);
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+ PyObject_ASSERT(FROM_GC(gc),
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+ gc->gc.gc_refs != 0);
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}
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}
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@@ -363,7 +432,9 @@ visit_decref(PyObject *op, void *data)
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* generation being collected, which can be recognized
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* because only they have positive gc_refs.
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*/
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- assert(gc->gc.gc_refs != 0); /* else refcount was too small */
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+ PyObject_ASSERT_WITH_MSG(FROM_GC(gc),
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+ gc->gc.gc_refs != 0,
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+ "refcount was too small");
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if (gc->gc.gc_refs > 0)
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gc->gc.gc_refs--;
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}
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@@ -423,9 +494,10 @@ visit_reachable(PyObject *op, PyGC_Head *reachable)
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* If gc_refs == GC_UNTRACKED, it must be ignored.
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*/
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else {
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- assert(gc_refs > 0
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- || gc_refs == GC_REACHABLE
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- || gc_refs == GC_UNTRACKED);
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+ PyObject_ASSERT(FROM_GC(gc),
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+ gc_refs > 0
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+ || gc_refs == GC_REACHABLE
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+ || gc_refs == GC_UNTRACKED);
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}
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}
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return 0;
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@@ -467,7 +539,7 @@ move_unreachable(PyGC_Head *young, PyGC_Head *unreachable)
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*/
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PyObject *op = FROM_GC(gc);
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traverseproc traverse = Py_TYPE(op)->tp_traverse;
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- assert(gc->gc.gc_refs > 0);
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+ PyObject_ASSERT(op, gc->gc.gc_refs > 0);
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gc->gc.gc_refs = GC_REACHABLE;
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(void) traverse(op,
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(visitproc)visit_reachable,
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@@ -545,7 +617,8 @@ move_finalizers(PyGC_Head *unreachable, PyGC_Head *finalizers)
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for (gc = unreachable->gc.gc_next; gc != unreachable; gc = next) {
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PyObject *op = FROM_GC(gc);
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- assert(IS_TENTATIVELY_UNREACHABLE(op));
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+ PyObject_ASSERT(op, IS_TENTATIVELY_UNREACHABLE(op));
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+
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next = gc->gc.gc_next;
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if (has_finalizer(op)) {
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@@ -621,7 +694,7 @@ handle_weakrefs(PyGC_Head *unreachable, PyGC_Head *old)
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PyWeakReference **wrlist;
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op = FROM_GC(gc);
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- assert(IS_TENTATIVELY_UNREACHABLE(op));
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+ PyObject_ASSERT(op, IS_TENTATIVELY_UNREACHABLE(op));
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next = gc->gc.gc_next;
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if (! PyType_SUPPORTS_WEAKREFS(Py_TYPE(op)))
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@@ -642,9 +715,9 @@ handle_weakrefs(PyGC_Head *unreachable, PyGC_Head *old)
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* the callback pointer intact. Obscure: it also
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* changes *wrlist.
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*/
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- assert(wr->wr_object == op);
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+ PyObject_ASSERT(wr->wr_object, wr->wr_object == op);
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_PyWeakref_ClearRef(wr);
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- assert(wr->wr_object == Py_None);
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+ PyObject_ASSERT(wr->wr_object, wr->wr_object == Py_None);
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if (wr->wr_callback == NULL)
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continue; /* no callback */
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@@ -678,7 +751,7 @@ handle_weakrefs(PyGC_Head *unreachable, PyGC_Head *old)
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*/
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if (IS_TENTATIVELY_UNREACHABLE(wr))
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continue;
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- assert(IS_REACHABLE(wr));
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+ PyObject_ASSERT(op, IS_REACHABLE(wr));
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/* Create a new reference so that wr can't go away
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* before we can process it again.
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@@ -687,7 +760,8 @@ handle_weakrefs(PyGC_Head *unreachable, PyGC_Head *old)
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/* Move wr to wrcb_to_call, for the next pass. */
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wrasgc = AS_GC(wr);
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- assert(wrasgc != next); /* wrasgc is reachable, but
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+ PyObject_ASSERT(op, wrasgc != next);
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+ /* wrasgc is reachable, but
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next isn't, so they can't
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be the same */
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gc_list_move(wrasgc, &wrcb_to_call);
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@@ -703,11 +777,11 @@ handle_weakrefs(PyGC_Head *unreachable, PyGC_Head *old)
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gc = wrcb_to_call.gc.gc_next;
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op = FROM_GC(gc);
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- assert(IS_REACHABLE(op));
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- assert(PyWeakref_Check(op));
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+ PyObject_ASSERT(op, IS_REACHABLE(op));
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+ PyObject_ASSERT(op, PyWeakref_Check(op));
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wr = (PyWeakReference *)op;
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callback = wr->wr_callback;
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- assert(callback != NULL);
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+ PyObject_ASSERT(op, callback != NULL);
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/* copy-paste of weakrefobject.c's handle_callback() */
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temp = PyObject_CallFunctionObjArgs(callback, wr, NULL);
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@@ -810,7 +884,7 @@ delete_garbage(PyGC_Head *collectable, PyGC_Head *old)
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PyGC_Head *gc = collectable->gc.gc_next;
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PyObject *op = FROM_GC(gc);
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- assert(IS_TENTATIVELY_UNREACHABLE(op));
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+ PyObject_ASSERT(op, IS_TENTATIVELY_UNREACHABLE(op));
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if (debug & DEBUG_SAVEALL) {
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PyList_Append(garbage, op);
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}
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